The official start of summer is June 21, but it's not too late to shape up and slim down before you hit the beach.

Fitness guru Harley Pasternak, the celebrity trainer behind the bikini-perfect bodies of stars like Jessica Simpson, Katy Perry, Megan Fox and more, shared 16 quick diet tips to help you reach your fitness goals and stay motivated each of the 16 days until summer and beyond.

"It doesn't require any surplus of money and it doesn't require a drastic amount of exercise or drastic amount of dieting," Pasternak, the author of "The Body Reset Diet,"told "Good Morning America."

1. Drink caffeinated tea or coffee. Studies show that 250 mg of caffeine consumed with a meal can increase the calories spent metabolizing the meal by 10 percent. Another study showed a 5 percent increase in daily calorie burn when consuming three cups of tea.

2. Eat smaller, more frequent meals.

Secrets for Your Best Beach Body from Jessica Simpson's Trainer

3. Add some avocado to your meals. Research shows healthy fats, like those found in avocados, can help keep you full between meals.

4. Spice it Up! Hot peppers, as well as chili peppers, contain capsaicin, which will cause the body to start expending more energy as heat, increasing your total calorie burn.

5. Behold, the power of protein! The addition of protein to your meal can increase your metabolism, according to research.

6. Sleep more to burn more. Studies have shown a link between poor sleep and higher body fat. A study from Brigham Young University found that people who get less than 6.5 hours of sleep and more than 8.5 hours of sleep have higher body fat.

7. Get fit with fiber. Make sure you have at least 10 grams of fiber with each meal (and 5 grams with each snack). Fiber will make you feel fuller longer and lowers your body's insulin response to sugar.

8. Get back! Focus on strengthening the muscles on the back of your body to create the illusion of a longer leaner body. See Pasternak's Fierce Five workout, which consists of four sets of 20 reps each of these: reverse lunges, single arm dumbbell rows, stiff leg dead lifts, lying dumbbell tricep extensions, plus four sets of minute planks to strengthen the core.

9. Take the stairs. Using an activity monitor, you should strive to stride a total of 14,000 steps a day, he says.

10. Call your friends on the go. Instead of sitting down to chat, take a walk and burn some calories at the same time.

11. Exercise while entertained. A study out of the University of North Carolina at Greensboro found watching a video while doing cardio significantly lowered your rate of perceived exertion, making it feel easier to exercise. And the more distractions, the better: Another study found those who exercised while listening to music and watching a personal TV completed longer exercise sessions than those who only listened to music or only watched TV.

12. Reign in your alcohol consumption, but not for the reason you think. Believe it or not, it's not only the extra calories from alcohol that make people gain weight. It's also because alcohol diminishes your ability to burn fat and weakens your inhibitions.

13. Got milk? Studies show that people who add more dairy to their diet can actually burn more fat. Try some Greek yogurt or cottage cheese.

14. Get up and walk. Get off the subway one stop earlier or park your car a block away.